Atlantic puffins in Spitsbergen, Norway, are different from those found further south
Rich Reid/Alamy
Two distinct subspecies of Atlantic puffins are now interbreeding in Norway, possibly as a result of Arctic warming forcing some birds away from their usual habitat.
The island of Spitsbergen in Svalbard, Norway, is inhabited by the largest subspecies of Atlantic puffin, known as Fratercula arctica naumanni. On the island of Røst, which is roughly 1000 kilometres to the south, there is a smaller subspecies called Fratercula arctica arctica.
In 2021, researchers discovered hybrid puffins – a mixture of these two subspecies – on Bear Island, which is located halfway between Spitsbergen and Røst and is also part of Norway. However, the exact timeframe of when this hybrid colony emerged was unknown.
Oliver Kersten at the University of Oslo in Norway and his colleagues conducted a study analyzing genetic samples collected from 22 puffins that lived between 1868 and 1910 on Spitsbergen, Røst, and Bear Island. They also examined the genomes of 18 modern puffins from these islands between 2012 and 2018.
Their analysis revealed that all puffins on Bear Island up until 1910 belonged to the subspecies F. a. arctica. Based on the analysis of the modern genomes, Kersten and his team believe that the interbreeding between the two subspecies began shortly after 1910.
“The appearance of this hybrid puffin population coincides precisely with the anthropogenic warming of the Arctic, which unexpectedly seems to have caused a southward shift of the naumanni subspecies from the high Arctic,” says Kersten.
“Rising temperatures reduced the food availability around Spitsbergen, forcing the naumanni puffins to search for food elsewhere,” he explains.
Currently, there are no major negative consequences of this hybridization since the distinct naumanni and arctica subspecies still exist on Spitsbergen and Røst. Kersten states, “Having the hybrid puffins actually adds genetic diversity. But there may be situations in the future where we lose genetic diversity because entire subspecies are forced to interbreed, resulting in only hybrid individuals.”
While similar hybridization events have not yet been observed among puffins in the UK and North America, Kersten suggests that if climate change continues displacing the birds from their natural habitats, this phenomenon may occur in the future.
“The southward movement of a typically Arctic subspecies challenges the idea that global warming will simply push species towards the poles,” says David Nogués-Bravo at the University of Copenhagen in Denmark. “It emphasizes the importance of anticipating and planning for diverse ecological responses to climate shifts.” However, a direct causal link between climate change and this hybridization has not yet been proven, Nogués-Bravo adds.
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